I lived in Davis CA when I was a driver and that is a very wealthy and expensive town to be in, and I had one professor throw an absolute fit because I couldn't give her coin change so she made her students dig through their pockets for exact change. It was a $150 order and I left without a tip and her reasoning was I had to get assistance to bring in the 10 pizzas, 12 2-liters of soda and all the plates, napkins and every other little thing she ordered.